Optoelectronic components on an organic basis, for example organic light emitting diodes (OLED), are being increasingly widely used in general lighting, for example as a surface light source. An organic optoelectronic component, for example an OLED, may include an anode and a cathode with an organic functional layer system therebetween. The anode or the cathode is conventionally formed from a metal. The organic functional layer system may include one or a plurality of emitter layer(s) in which electromagnetic radiation is generated, one or a plurality of charge generating layer structure(s) each composed of two or more charge generating layers (CGL) for charge generation, and one or a plurality of electron blocking layer(s), also designated as hole transport layer(s) (HTL), and one or a plurality of hole blocking layer(s), also designated as electron transport layer(s) (ETL), in order to direct the current flow.
Individual layers of an OLED can conventionally be formed by different methods, for example by vapor deposition or wet-chemical methods.
During the production of an optoelectronic component, individual layers of the optoelectronic component are conventionally formed, for example deposited, successively above a substrate. The layers can be structured laterally during the deposition or afterward. Layers are structured laterally in order, for example in a functional thin-film system, to apply different layers of the functional thin-film system to in part different lateral regions of the substrate.
In the case of lateral structuring of a plurality of stacked thin functional layers during their deposition onto a substrate, the lateral structuring methods of the plurality of layers can mutually disturb one another. By way of example, the lateral structuring of the organic functional layer structure and the structuring of the metallic top electrode of an OLED during a physical vapor deposition of these layers can mutually disturb one another. During the production of a conventional OLED, it is necessary to apply the organic functional layer structure and the cathode in conjunction with partial overlapping in laterally different, defined regions on the substrate. For this purpose, during an inherently unstructured physical vapor deposition, the substrate is masked, i.e. “shaded”, such that the deposited materials are deposited on the substrate only in the regions provided by the regions of the mask that allow passage. Particularly when producing OLEDs, metallic shadow masks are conventionally used for structuring layers during the physical vapor deposition. The metallic shadow masks 104 are arranged closely in front of the substrate 102 to be coated (illustrated in FIG. 1A). The shadow mask 104 has an opening, through which a coating 106 is applied to the substrate 102. Illustratively, the shadow mask 104 in the region without an opening shades the substrate 102 against a coating application during the process of forming the coating 106. In conventional methods, the shadow mask 104 is arranged above the substrate 102, such that the shadow mask 104 and the substrate 102 have no physical contact. As a result, it happens that during the process of coating the substrate 102 in the penumbra at the edges of the opening of the shadow mask 104 on the substrate 102 in the actually shaded region of the substrate 102 a coating 106 is formed (identified by the encircled area bearing the reference sign 108). The production and use of metallic shadow masks is a relatively cost-intensive process. The production of metallic shadow masks can prove to be complex, for example laser cutting and/or wet-chemical production including photoresist coating, photolithographic patterning and subsequent etching. Furthermore, the metallic shadow masks can be coated during the physical vapor deposition. Therefore, conventionally these “coats” are often cleaned from the metallic shadow masks and the latter are regularly replaced. In order to be able to perform a plurality of coating steps in which different regions are coated, the metallic masks are changed during the coating process. Changing the metallic masks is associated with a considerable time expenditure, which has unfavorable effects on the cycle time of the production of the component. Furthermore, conventional metallic masks have a disadvantage resulting from their use with regard to the lateral structuring. By way of example, without very complex multi-mask processes it is not possible to realize “free-standing” uncoated regions within a coated area. In the case of an OLED, therefore, with a simple metal mask process, it is neither possible to produce independent luminous regions within another luminous region, nor possible to produce open non-luminous regions within a luminous region.
Furthermore, regions not to be coated between coated regions have a minimum distance of a few millimeters. Otherwise the thin webs of the metallic mask would not have the necessary stability and might sag. Therefore, it is not possible, with a simple, conventional shadow mask process, to form individual luminous regions alongside one another on a substrate, without accepting large non-luminous dead regions.
In the field of microstructuring for microelectronic components, for example transistors, it is known to use film masks 110 (illustrated in FIG. 1B). In this case, a film is laminated onto a substrate 102 to be coated. Afterward, the film is microstructured, i.e. partly opened, for example by a laser ablation. Afterward, the film is coated over the whole area. The film is subsequently stripped away from the substrate. The applied material remains on the substrate 102 only in the regions of the film 110 that were opened beforehand by the microstructuring step. As a result, after removal of the film mask 110, a coating 106 having defined edges (illustrated by the encircled area bearing the reference sign 112), can be formed on the substrate 102. Two or more film masks lying one on top of another can conventionally be used, wherein film masks lying one on top of another conventionally are structured simultaneously and identically in the same microstructuring step. As a result, coating is carried out in the resultant free regions of the two films. After the process of stripping away only the upper film of the films lying one on top of another, the coated material remains in the exposed region and in this case is laterally enclosed by the lower film remaining on the substrate. Furthermore, conventional methods do not provide for defining different open regions in both film masks, i.e. the first mask film is not structured before the second mask structure is applied.
It is furthermore known to use film masks for the production of OLEDs or OLED displays. For this purpose, a masking film is applied to a substrate. The masking film is structured into a plurality of regions; into masking regions and regions for openings. A removal film is applied to the masking film and adhesively bonded to the masking film in the regions for openings. The removal film is stripped away with the adhesively bonded regions of the masking film, such that a mask film having open regions remains on the substrate. Afterward, the substrate is coated with material. After the first coating step, the mask film is stripped away, such that only material in the envisaged regions remains on the substrate. Alternatively, the first mask film initially remains on the substrate and the entire process is repeated with one or a plurality of further mask films. The resultant multiple stack of mask films is finally removed in its entirety after the last coating step in a single process. As a typical use example, provision is made for applying the organic emitter material of the three subpixels (red, green and blue) required per pixel for a display successively in different positions on the substrate.
It is furthermore known to use a film mask for structured coating of a substrate with a single layer in a roll-to-roll method. For this purpose, a prestructured mask film is continuously laminated onto a substrate film, the latter is coated, and the mask film is subsequently stripped away.
Furthermore, in conventional methods, microscopic free regions are directly structured into the mask structure on the substrate, e.g. by laser ablation. In the case of large-area optoelectronic components, the method duration can lengthen as a result.
Furthermore, in one conventional method, a second mask film is applied to the substrate and structured only after a first coating step has been carried out. In this case, therefore, applying and structuring the second film take place between the first and second coating steps.
Furthermore, in one conventional method, a mask film is removed from the substrate by adhesive bonding of a further film and subsequent lift-off of the further film with the mask film.